Trencher having an endless digger and adjustable augers

ABSTRACT

AN ADJUSTABLE BOOM CARRYING AN ENDLESS DIGGING CHAIN OPRATED HYDRAULICALLY AND HAVING A DOWNWARDLY EXTENDING OFFSET TIP WITH THE END OF THE BOOM ADJUSTABLE FOR CHAIN LOOSENING AND TIGHTENING. TRANSVERSE AUGERS MOVE EXCAVATED DIRT AWAY FROM THE TRENCH FORMED BY THE DIGGING CHAIN AND THESE ARE ADJUSTABLE ALONG THE LENGTH OF THE BOOM TO COMPENSATE FOR THE SWINGING MOVEMENT TO THE BOOM WHICH ALLOWS A TRENCH TO THE DUG AT VARIOUS DEPTHS AS THE DIGGING PROCEEDS.

Dec. 7, 1971 R. G. LAWRENCE TRENCHER HAVING AN ENDLESS DIGGER ANDADJUSTABLE AUGERS Filed Sept. 2, 1969 5 Sheots-Shcot 1 m "P T T an $0 :02' m n 0 IO INVUNTOR ALBERT HWRE/Vaa BY v' vA- v (.212,

ATTORNEY R. e. LAWRENCE 3,624,935

TRENCHER HAVING AN ENDLESS DIGGER AND ADJUSTABLE AUGERS Dec. 7, 1971 5Sheets-Sheet 2 Filed Sept.

INVENTOR Dec. 7, 1971 R. a. LAWRENCE 3,624,935

TRENCHER HAVING AN ENDLESS DIGGER AND ADJUSTABLE AUGERS Filed Sept. 2,1969 I5 Sheets-Sheet 5 FIG 4 FIG. 7

FIG. 5

INVENTOR 754% v (lee,

ATTORNEY United States Patent 3,624,935 TRENCHER HAVING AN ENDLESSDIGGER AND ADJUSTABLE AUGERS Robert G. Lawrence, Swift Current,Saskatchewan, Canada, assignor to Saskatchewan Power Corporation,Regina, Saskatchewan, Canada Filed Sept. 2, 1969, Ser. No. 854,459 Int.Cl. E021 5/06 U.S. Cl. 37-86 2 Claims ABSTRACT OF THE DISCLOSURE Anadjustable boom carrying an endless digging chain operated hydraulicallyand having a downwardly extending offset tip with the end of the boomadjustable for chain loosening and tightening. Transverse angers moveexcavated dirt away from the trench formed by the digging chain andthese are adjustable along the length of the boom to compensate for theswinging movement of the boom which allows a trench to be dug at variousdepths as the digging proceeds.

This invention relates to new and useful improvements in hydraulictrenching devices, particularly devices adapted to form or cut a trenchfor the installation of gas lines or the like.

Conventional trenchers normally utilize an endless chain having cutterblades or semi-buckets thereon and these are rotated on a boom which canbe raised or lowered with relation to the ground. They are normallydriven from the source of power such as tractor, by means of chain driveand are normally provided with a transverse auger which moves theexcavated soil away from the cut upon either side thereof.

The present invention consists of several improvements in existingdevices.

Firstly, the trenching chain is driven directly by an hydraulic drive.The hydraulic motors are coupled directly to the final drive shaft ofthe trenching device thereby eliminating all side load on the hydraulicmotors and accomplishing a power transmission by torsional load only.This assures long hydraulic motor life under the severe conditionsencountered by this type of machine.

Secondly, the hydraulic drive permits a reversible digging chainassembly. In other words the chain can travel in either a forwardtrenching direction or a reverse trenching direction.

The need for this type of operation occurs particularly in rocky land orin areas where yards are completely landscaped with hedges, shrubs,sidewalks, driveways and the like. The reversible chain allows themachine to undercut such shrubs, driveways and the like to a certainextent without damaging them.

The reversible chain also allows the operator to back off the chain it arock becomes jammed between various drive components and the chain. Thisoften happens in rocky terrain.

The hydraulic drive on the trenching device itself eliminates a greatportion of shock load to the structural portions of the machine, thusdecreasing the amount of maintenance necessary on all parts andespecially on the digging chain assembly itself. The hydraulic drivealso offers numerous digging chain speeds which is particularly suitedto frost conditions and for the purpose of Bell-holing.

A second improvement is the fact that the transverse soil clearing angeris adjustable hydraulically. The purpose of these angers on thetrenching device is to move the excavated dirt into small spoil piles asthe trencher progresses in a forward direction. This is best accom-3,624,935 Patented Dec. 7, 1971 plished by keeping the anger at abouttwo inches from ground level, therefore it is necessary to be able toadjust the augers as various trench depths are desired.

For example, in the process of trenching a gas service, it is generallynecessary to vary the depth of trench from thirty inches toapproximately five feet in order to provide suflicient ground cover inthe first instance and in the second instance to reach the gas main fortie-in purposes. The operator must therefore be able to adjust the augerheight with relation to the boom as he proceeds along the trench. Thepresent system incorporated in this device allows a variable adjustmentat any time and during the operation of the machine.

A third important improvement is the fact that the digging chainassembly can be varied so far as tension is concerned. A device isincorporated on the outer end of the boom which again is controlled bythe use of an hydraulic cylinder. This allows the chain tension to beadjusted continuously by the operator for the following reasons.

Firstly, due to the design of the variable auger adjustment, the chainmust be adjusted at the same time as the augers in order to maintain thecorrect tension on the chain.

Secondly, depending upon the type of soil in which the machine isoperating, the digging chain should be adjusted to maintain a propertension or slack in the digging chain as the case may be. For instance,when operating on frozen soil, the digging chain should be relativelytight, thus preventing bounce or snap in the digging chain.

In soil with gravel or small rocks, the digging chain should berelatively loose, thus allowing these rocks to squeeze out rather thanbind in between the chain link and sprockets.

Thirdly, if an object becomes jammed in the chain and it is impossibleto rotate the digging chain in the opposite direction by use of thehydraulic motors, it is possible to slacken the digging chain, thusallowing the object to fall free of the boom.

The fourth important improvement is the provision of an offset cuttingtip at the end of the boom. The outer sprocket wheel on the presentdevice is offset from the boom axis downwardly by approximately fourinches. The purpose for this is when digging in extremely toughconditions such as frost or dry gumbo type soil, it is necessary toreduce the effective cutting length of chain down to a minimum number ofteeth in contact with the ground, thus getting a higher degree ofbreakout force at the teeth in contact with the soil. This offset headaccomplishes this purpose thereby allowing the device to trench inextremely tough digging conditions.

With the foregoing in view, and such other or further purposes,advantages or novel features as may become apparent from considerationof this disclosure and specification, the present invention consists ofthe inventive concept which is comprised, embodied, embraced or includedin the method, process, construction, composition, arrangement of parts,or new use of any of the foregoing, herein exemplified in one or morespecific embodiments of such concept, reference being had to theaccompanying figures in which:

FIG. 1 is a top plan view of the boom assembly with the chain andtransverse anger removed for clarity.

FIG. 2 is a side elevation of FIG. 1 showing the chain in dotted line.

FIG. 3 is a side elevation of the offset cutting tip per se, enlarged inscale in respect to FIGS. 1 and 2.

FIG. 4 is an end view of the transverse auger sliding support.

FIG. 5 is an end view of the boom showing the auger carrier slide.

FIG. 6 is a schematic view of the hydraulic system for the trencher.

FIG. 7 is a schematic View of the hydraulic accesory and tractor creepercircuitry.

In the drawings like characters of reference indicate correspondingparts in the different figures.

Before proceeding with the description of the device, it should beappreciated that it is designed to be attached to the rear of a tractoror similar source of motive power having a source of power for theoperation of the hydraulic systems. The boom assembly shown in FIGS. 1and 2. is adapted to be mounted for vertical raising and lowering uponthe rear of the tractor, said raising and lowering being operatedhydraulically as will hereinafter be described.

Proceeding therefore to describe the invention in detail, referencecharacter 10 shows the main boom which is of square cross section and ispreferably hollow not only for weight considerations but also so thathydraulic lines and boom tip extension cylinder can be located therein.

The rear end 11 of the boom is enlarged as illustrated and a crossmember 12 also of square cross section is secured upon each side of thisenlarged portion. Brackets 13 extend rearwardly from the ends of thecross members 12 by which the device may be mounted for theaforementioned vertical pivoting action. An hydraulic piston andcylinder assembly 14 (see FIG. 7) is secured upon each side of the boomjust forwardly of the cross members 12 between clevises 15 and extendupwardly to the main supporting frame extending from the tractor (notillustrated). These are connected to the. hydraulic pump 16 and operatedthrough a four-way valve 17' so that the main boom assembly may beraised and lowered within limits.

The transverse auger assembly collectively designated 17 consists of ananger section 18 upon each side of the boom flighted in oppositedirections so that if the auger assemblies are rotated in one direction,and soil engaged thereby is urged outwardly away from the boom upon eachside by the two sections.

These are mounted on a shaft 19 in turn supported within pillow blocks20 (see FIG. 4). These pillow blocks are secured to the underside of anauger carrier 21 which consists of a main body portion 22 having reverseangle plates 23 secured to the upperside thereof as clearly shown inFIG. 4.

These angle plates engage over longitudinally extending rails or plates24 which in turn are secured in spaced relationship from the underside25 of the main boom, said spaced relationship being provided for by theelongated strip 25 as clearly shown in FIG. 5.

An hydraulic piston and cylinder assembly 26 is pivotally secured by oneend 27 to a bracket 28 which in turn extends rearwardly from side plates29 secured to the underside of the boom. The piston rod 30 extendingfrom the piston and cylinder assembly 26, is secured by means of aclevis (not illustrated) to the aforementioned auger carriage body 22 sothat extension or retraction of the piston rod 30 causes the augerassembly 18 to be moved fore and aft with respect to the boom, it beingunderstood that in operation, the boom extends downwardly and forwardlyfrom the tractor on an inclined plane.

Secured to the rear bifurcated portions 11A and 11B of the enlargedportion 11, is a pair of pillow blocks 31. A main drive shaft 32 isjournaled for rotation within these pillow blocks and a main drivesprocket wheel 33 is secured to this shaft.

Hydraulic motor mounting plates 34 are secured fo the rear sides 35 ofeach of the transverse extensions 12 and hydraulic motor mounts 36extend outwardly from these plates at right angles thereto. Hydraulicmotors 37 are secured to these plates and are coupled directly to eachend of shaft 32 and these are connected to a further pump 38 (see FIG.6) operated by a gas engine 39 or similar source of power.

A four-way valve 40 determines the direction of rotation of these motorsand hence the direction of rotation of the main drive sprocket wheel 33.

An idler sprocket wheel 41 is journaled for rotation between the twoside plates 29 hereinbefore described and further idler sprocket wheels41A and 41B are journaled for rotation between corresponding side plates29A and 29B extending upwardly from the upper side 42 of the main boom10.

An offset tip assembly collectively designated 43 extends forwardly anddownwardly from the end 44 of the main boom assembly 10 and is shown indetail in FIG. 3. It consists of a square cross sectioned main bodyportion 45 slidably receivable within the end 44 of the main boom andbeing capable of limited extension with relation thereto. A piston rod46 is pivotally secured within the end 47 of this portion 45, by meansof transverse pin 48 and this piston rod forms part of a piston andcylinder assembly 49 operated by four-way valve 50* shown in FIG. 7.

And endless digging chain assembly 51 having cutter blades 52 thereon,extends around the idlers 41, 41A, and 41B, and around the main drivesprocket 33. It also extends around a sprocket wheel 53 journaled forrotation upon shaft 54, mounted between end plates 55 extending from theend 56 of the tip assembly 43. It should be observed that these endplates incline forwardly and downwardly from the end 56 so that pin 54is below the longitudinal axis of the tip body 45 and the boom 10.

This means that when the boom is inclined downwardly, a relatively smallnumber of teeth engage the soil thus assisting in breaking through thissoil under tough conditions as hereinbefore described.

The aforementioned piston and cylinder assembly 49 controlling theextension and retraction of the tip assembly 43 within the end 44 of theboom, permits the tension of the chain 51 to be adjusted Within limitsas hereinbefore described.

Reference to FIG. 7 will show that a further four-way valve assembly 57operates the piston and cylinder assembly 26 for the auger adjustmentand also in this circuit, a further four-way valve assembly 58 controlsan hydraulic motor 59. This motor 59 is connected to the drive of thetractor or source of power thus allowing it to be moved forwardly at arelatively low speed, said speed being infinitely variable within limitsdue to the characteristics.

Both FIGS. 6 and 7 show conventional control valves and the like incircuit with the hydraulic systems but as these are conventional, it isnot thought necessary to describe sa'me in detail.

From the foregoing it will be appreciated that a boom assembly isprovided in which the chain assembly is driven directly by hydraulicmotors thus giving variable speed and forward and reverse operations tothe digging chain assembly.

Furthermore it will be appreciated that the tension of the chainassembly 51 can be varied within limits by the extension and retract ofthe tip 43. In this connection also it should be observed that the idlersprocket wheel 53 mounted in the tip is below the longitudinal axis ofthe boom.

Next it should be appreciated that the transverse auger 18 can beadjusted within limits along the length of the boom thus regardless ofthe depth at which the auger is cutting.

Finally it should be observed that the hydraulic motor 59 allows thesource of power such as a tractor to be controlled as to the forward andreverse speeds, easily and readily and at a speed suited to the diggingconditions.

Various modifications can be made within the scope of the inventiveconcept disclosed. Accordingly, it is intended that such concept and notfor the purpose of limiting protection to any particular embodimentthereof, but that only such limitations should be placed upon the scopeof protection to which the inventor hereof is entitled, as justicedictates.

What is claimed to be the present invention is:

1. In a trenching device adapted to be supported upon a source of motivepower and including a source of hydraulic pressure; a boom pivoted byone end thereof to said source of motive power, an endless digging chainmounted around said boom for movement thereon, an hydraulic motoroperatively connected to said endless chain for rotatably moving saidchain in either direction around said boom, a pair of transverselysituated oppositely flighted, auger assemblies, one upon each side ofsaid boom and situated externally of said chain, means to move saidtransverse auger assemblies along the length of said boom within limits,a downwardly offset tip on said boom and a sprocket journalled in saidtip, said digging chain engaging around said sprocket, said means tomove said transverse auger assembly along the length of said boom withinlimits, including a longitudinally extending rail secured to theunderside of said boom, an augar carrier slidably mounted on said railfor longitudinal movement therealong, an auger shaft journalled forrotation transversely of said carrier, an hydraulic piston and cylinderassembly operatively connected between said boom and said carrier formoving same along said rail.

2. The device according to claim 1 in which the other end of said boomis movable inwardly and outwardly within limits, relative to theremainder of said boom, for adjusting the tension in said digging chain.

References Cited ROBERT E. PULFREY, Primary Examiner C. D. CROWDER,Assistant Examiner US. Cl. X.R. 37191 A

